The present invention relates to a method for controlling a storage system and storage subsystem, and more particularly to a method for controlling a storage system that virtualizes a resource and apparatus thereof.
In an information processing system, there is a possibility that processing in a computer is aborted by a program bug executed in the computer, or the like, causing data included in the information processing system to be in a state of contradiction. In addition, data managed by the information processing system may be erased by human error.
In order to reliably restore the data of the information processing system, which is in such a state, the information processing system generally obtains a backup of the data on a routine basis. Japanese Patent Application Laid-Open No. 2000-132343 describes a storage subsystem which creates a still image copy (snapshot volume), data consistency of which is maintained, in order to obtain a backup without hindering an access to data to be backed up.
According to a snapshot creating method described in the document, data is copied between a source volume and a target volume specified by a host computer, and control such as copy stop for making data still (separation of a volume pair), and data resynchronization, is performed on a volume basis. Such a snapshot volume is used not only for obtaining a backup, but also for realization of a data shift, and data sharing, in which data consistency between databases is maintained.
In addition, Japanese Patent Laid-Open No. Hei 9-274544 describes a storage subsystem which associates storage areas (address conversion) between a logical volume accessed by a host computer and a physical storage device in which data stored in the logical volume is actually stored to process an access, in which there is obtained information about an access from the host computer to the logical volume, and the association is changed to perform physical relocation so that an optimum allocation of the stored data is realized.
Moreover, in Japanese Patent Laid-Open No. Hei 10-333839 and Japanese Patent Laid-Open No. 2000-276406, a storage subsystem characterized by the following is described: when a storage subsystem is accessed from a host computer, using a WWN (WORLD WIDE NAME), which uniquely identifies a fiber channel interface (hereinafter referred to as port) of the host computer, to judge whether or not an access from the host computer to a logical volume of the storage subsystem is allowed; and if a port has no permission, refusing the access to the port.
In recent years, information processing systems have a problem that management cost for a storage device and a storage area increases because data used in the storage device and the storage area has enormously increased. In light of this, “Virtualizing the SAN” (Jul. 5, 2000), which is a report by Morgan Keegan, a research company, shows a system that virtualizes a logical volume, which is provided by a storage subsystem, according to a request from a host computer, and that provides a host computer with this virtual volume that has been virtualized.
In this report, several kinds of system configurations that realize the virtualization are described.
One system is characterized by the following: connecting a computer for realizing the virtualization between a host computer and a storage subsystem; and by using this computer, providing the host computer with an area constituted of one or more volumes as a virtual volume for converting an access from the host computer to the virtual volume into an access to a corresponding logical volume.
For another example, a host computer is connected to a storage subsystem; and a computer which manages an association of a storage area as a logical volume with an area as a virtual volume is connected to the host computer. When the host computer accesses the virtual volume, the host computer sends an inquiry to the computer about a location of data to be accessed on the virtual volume. The computer returns a location of the logical volume corresponding to the virtual volume to the host computer. The host computer accesses the volume provided by the storage subsystem using the received information about the location of the logical volume.
As used herein, the term “storage subsystem” refers to a storage apparatus or device including one or more storage controllers configured to process information and one or more storage components configured to store data (e.g., disks, tapes, etc.). Examples of storage subsystems include disk array units.
As used herein, the term “storage device” or “storage unit” refers to any storage apparatus configured to store data therein. Examples of storage devices include storage subsystems, hard disk drives, CD-ROMs, and magnetic tapes.
As used herein, the term “storage system” refers to a system including one or more storage device that is coupled to one or more information processing unit. Examples of storage systems include storage area network systems, network area storage systems, and storage subsystems.